'Motion detection'? In a lavatory?
Speaking of not being able to smoke on a long flight.

Nothing worse than feeling like **** already going through withdrawals and dry from the flight and a bit sweaty to arrive in a hot place and the first thing you do is light up as soon as you can get a chance too. You've arrived and you are already grumpy.

It's not even a nice cigarette.

and that's right Burney Motion detection.
If you go in there and dance like something from tales of the unexpected it will also set them off.